Glass fiber reinforced resin tank structures and method of fabricating

ABSTRACT

1. A method of on-site fabrication of glass fiber, reinforced, plastic-resin tank structures, using a plurality of pre-fabricated, structural, arcuate liner panels of glass fiber, reinforced resin, comprising: providing a base support for the tank structure, temporarily securing vertical support and alignment beams to the base support at spaced intervals corresponding to the width of the liner panels to define the circumference of the tank structure, the beams extending the height of the tank structure, providing a central beam extending upwardly from the base support having a plurality of lateral arms extending therefrom into contact with the temporary vertical support beams to support the side walls of the structure during fabrication thereof, temporarily securing by removable rivets the liner panels to the vertical support and alignment beams, the panels extending the height of the beams and abutting each other along their side edges in coincidence with the vertical support beams to define the side walls of the tank structure, providing a top cover for the tank structure of glass fiber, reinforced resin, securing the top cover to the top edges of the liner panels, applying a mixture of chopped glass fiber and resin over the joint areas between the abutting liner panels and between the top cover and the top edges of the liner panels to seal them and form an integral tank structure, mixing resin and catalyst together for impregnation of continuous glass fiber roving for winding of the side walls of the tank structure closely adjacent the point of application of the resin-impregnated glass fiber to the side walls, impregnating the glass fiber roving with the resin catalyst mixture, winding successive layers of the resin-impregnated continuous glass fiber roving around the outer surfaces of the liner panels in a helical pattern extending spirally both upward and downward to provide hoop strength for the tank structure, removing the support and alignment beams temporarily secured to the liner panels from the interior of the tank structure after curing of the resin, and applying resin-impregnated chopped glass fiber over the inner portion of the base support surrounded by the liner panels and joint areas between the lower ends of the liner panels in the base support to form an integral bottom wall for the tank structure.

Oct. 22, 1974 w JESSUP 3,843,429

GLASS FIBER REINFORCED RESIN TANK'STRUCTUR OD 015' FABRICATING AND METHOriginal Filed Sept. 18, 1970 3 Sheets-Shet 1 FIG? 1 WALLACE. B-JESSUPINVENTOR.

ATTORNEYS w. B.- JESSUP Oct. 22, 1974 3,843,429 GLASS FIBER REINFORCEDRESIN TANK STRUCTURES AND METHOD 0F FABRICATING 1970 3 Sheets-Sheet 2Original Filed Sept. 18,

F1IG=5 FIG== F1IG==6 WALLACE B.JESSUI5 V h u n FIIG-=7 ATTORNEYS Oct.22, 1974 w. B. JESSUP GLASS FIBER REINFORCED RESIN TANK 3,843,429STRUCTURES AND METHOD OF FABRICATING Original Filed Sept. 18, 1970 3Sheets-Sheet 5 P U S S E v 8 w M M W WWU B ATTORNEYS Int. Cl. B29c27/28; B65h 81/04 U.S. Cl. 156-69 13 Claims ABSTRACT OF THE DISCLOSURELarge tank structures are fabricated on-site of glass fiber reinforcedresin. A prefabricated top cover of chopped and woven fiber reinforcedresin of predetermined circumference is hoisted up a distance equal toat least the height of the tank. Temporary support beams of choppedfiber reinforced resin, metal, wood or other suitable material aresecured in 'vertical position to a base support for the tank atregularly spaced intervals around the designated circumferential area ofthe tank. Structural, prefabricated, arcuate liner panels of choppedand/or woven fiber reinforced resin are then secured temporarily to thesupport beams, the liner panels abutting one another and extendingbetween the beams to define the side walls of the tank structure. Theedges of the top cover are rested on the top edges of the side wallspanels. The joints between the abutting panels and be- 'with choppedand/or woven fiber for added stiffness and longitudinal strength. Aftercuring of the resin-fiber composite, the temporary internal supportbeams are removed and the inner seams of the arcuate panels sealed witha composite of fiber and resin. The bottom of the tank is formed andjoined to the side wall using a resinfiber composite with the tank basesupport acting as a form for the bottom material. Prefabricated fittingsand appurtenances are installed and welded into the tank structure witha resin-fiber mixture.

This is a continuation of application Ser. No. 73,538, filed Sept. 18,1970, now abandoned.

BACKGROUND OF THE INVENTION Field of the Invention This inventionrelates to fiber reinforced tank structures and to a method offabricating such.

Prior Art Relating to the Disclosure On-site fabrication of fiberreinforced resin tanks has been accomplished by filament windingsegments of the tank either off-site or on-site and bonding the segmentstogether at the use site. Other means of fabricating fiber resinreinforced tanks are disclosed in U.S. Pat. Nos. 2,729,268 to Broughtonet a1. and 3,470,656 to Clements. The method of fabrication described byboth of the above mentioned patents employs internal mandrels over whichthe reinforcing fibers wetted with resin are wound. After curing of theresin the inner mandrels are removed. Contrary to the method offabrication disclosed United States Patent O in the patents, the tankstructure of this invention em- I 3,843,429 Patented Oct. 22, 1974 iceploys structural, arcuate liner panels over which resin impregnatedfiber filaments are applied in successive layers. The liner panels arean integral part of the tank structure in that they furnish structuralsupport for the tank and provide a sealer for the contents of the tank.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a tankstructure of this invention prior to circumferential winding of the sidewalls with successive layers of continuous resin-impregnated fiber oralternating layers of chopped fiberresin and continuousresin-impregnated fiber;

FIG. 2 is a cross sectional view of the tank structure of FIG. 1 showingthe tapered outer side walls made up of successive convolutions of curedresin-impregnated fiber;

FIG. 3 is a sectional view along section line 33 of FIG. 2 illustratingthe configuration of the temporary support beams and their manner ofattachment to the arcuate liner panels;

FIGS. 4 to 7 illustrate steps employed in the method of fabricating thetank structures of this invention;

FIG. 8 is an isometric view of the winding machine used to laysuccessive or alternating layers of continuous resin-impregnatedfilaments over the arcuate panels forming the side walls of the tankstructure;

FIG. 9 is a plan view of the winding machine of FIG. 8; and

FIG. 10 is a partial isometric view of the means for securing the upperportion of the tower of the winding machine to the mast extendingthrough the top of the tank structure.

DETAILED DESCRIPTION OF THE INVENTION of large tanks has been quiteexpensive by prior art methods because of the amount of hand laborrequired and the elaborate internal mandrels used. The tank structure ofthis invention can be fabricated on-site with ease, employing a minimumof hand labor and making efficient use of temporary structural supports.

For on-site fabrication a support slab 1 of concrete or other suitablematerial is provided for erection of the tank thereon.

The finished tank of this invention may be an open top tank or a closedtop tank. If a top cover is desired, the cover may be fabricated from aseries of pie-shaped sections bonded together by applying a mixture ofchopped and woven glass fiber and uncured resin over the joints betweenthe sections. The side walls of the tank of this invention have an innersurface formed by a series of arcuate, structural liner panels abuttingeach other and defining the circumference of the tank. Both the topcover sections and the liner panel sections may be prefabricated eitheronsite or off-site to the size desired. FIG. 1 illustrates the tank,prior to filament winding of the side wall. The top cover 2 is formed ofa series of pie-shaped sections 3 and the side walls 4 of a series ofarcuate panel sections 5. The pie-shaped sections 3 have ribbed portions6 integral therewith for reinforcement. At the outer end of each of thepie-shaped sections is a downwardly extending flange 7. In the center ofthe top cover is an opening 8. Each of the pie-shaped sections isformed, preferably of chopped fiber and resin sprayed over a mold orform. Sufficient material is sprayed over the mold to form sections ofdesired thickness.

The liner panels 5 provide longitudinal strength for the structure andare fabricated by applying a mixture of resin and chopped fiber onto anarcuate form, the arc corresponding to that required for the diametertank being 3 built. The height of the panels is substantially equal tothe height of the tank with the thickness ofthe panels adequate to meetthe design requirements. A preferred way of forming the arcuate panelsis to provide a horizontal form or mold having the requisite are overwhich is sprayed a mixture of resin and chopped fiber, the Spraying headbeing mounted for both longitudinal and lateral movement over the moldor forming surface. By mechanical, hydraulic or electrical programmingthe spraying head is controlled in its longitudinal and lateralmovements to produce panels of uniform thickness and quality. Preferablythe longitudinal edges of each of the panels is bevelled so that, whenthe abutting edges of the panels are joined by application offiber-resin composite over the joint areas, the outer surface of theside walls is uniform.

FIGS. 4 to 6 illustrate steps in the fabrication of a tank structure.

Referring to FIG. 4 a mast 9 is erected, generally in the center of thecircumferential area to be occupied by the tank, the mast being highenough to extend above the top of the tank a predetermined distance. Themast is used for several purposes: (1) to support the top cover sectioninitially while the support beams are being fitted into place, (2) forerection of lateral arms extending outwardly therefrom to aid thesupport beams in supporting the side walls during filament windingthereof, and (3) to support a cover or housing for the entire tankstructure to shield it against weather conditions during fabrication.

The top cover may be fabricated on the support slab 1 around mast 9 bywelding prefabricated pie-shaped sections 3 together. After the weldedjoints have sufficiently cured guy wires 10 extending upwardly throughthe mast from a winding spool 11 and over idler rolls 12 are attached tothe top cover 2, at predetermined points. The top cover 2 is thenhoisted upwardly manually or by power means to the position shown inFIG. 4. Structural support beams 13 are then erected as shown in FIG. 5.These may be of wood, steel or other suitable material. For example,they may be fabricated from chopped fiber and resin by forming them overa mandrel in a conventional manner. The support beams 13 are fastened orsecured to the support slab 1 at spaced intervals around thecircumference to be occupied by the tank by any suitable means such asrivets, bolts, etc. The upper ends of each of the beams extend under thetop cover 2 inside of the flange 7 on each of the pie-shaped sections 3.

If a tank twenty or more feet in height is being fabricated it isdesirable to provide laterally extending arms 14 (see FIG. 5) part wayup mast 9. The arms extend between mast 9 and support beams 13 and aidin keeping the beams in alignment during filament winding of the outersurface of the side walls. If a tank of less than ten feet in height isfabricated the arms are not generally necessary.

The arcuate liner panels are secured by rivets 15 (see FIG. 2) or othersuitable means to beams 13, the panels abutting each other along theirside edges and extending between the support beams. The top edges of theliner panels abut the lower edges of flange 6 of the pie-shaped sections3, making up the top cover 2 as shown in FIG. 2.

The joints between each of the abutting panels 5 and the joints betweenthe upper edges of panels 5 and the lower edges of flanges 6 of the topcover are welded together prior to filament winding of the side walls ofthe tank with a mixture of chopped fiber and resin applied over thejoints, thereby providing a tank structure having an inner liquid seal.The joints are usually sealed by applying resin-impregnated choppedglass rovings with a conventional spray gun. Joint areas may also besealed manually if desired.

To wind the side walls with continuous resin-impregnated glass fiber awheeled carriage is provided, the carriage supporting a filament supplycomprising a plurality of sources 21 of glass rovings or filaments;Secured to the wheeled carriage 20 is an elevated mast 23 extending theheight of the tank or higher. The mast 23 is supported at its upper endwith a support arm 24 extending horizontally out from a rotating joint25 positioned on the support mast 9. The rotating joint includes acylindrical track 26 surrounding mast 9 and attached thereto by means ofsuitable brackets. Support arm 24 includes a U-bracket at one end onwhich are attached sets of rollers 27, each setof, rollers positioned tocontact the upper and lower track surfaces of track 26. A platform 28 ismounted for travel up and down mast 23 along tracks defined by two ofthe vertical supports of mast 23. The platform is secured to chain 29,trained around rotatable sprockets at the upper and lower ends of themast 23. Only the lower sprocket 22 is shown in FIG. 8. Chain 29 and theplatform 28 are driven by rotation of the wheels of the carriage throughsuitablegear reduction means 30. A layup arm 31 is secured to theplatform 28 and moves therewith. The carriage 20 contains suitable powermeans for driving the wheels thereof. The layup arm 31 travels up anddown the mast 23 a predetermined amount per rotation of the carriagearound the tank. The ratio of upward travel of the layup arm perrevolution of the carriage around the tank is adjustable. Generally, theratio of upward travel of the layup arm per revolution of the carriageis about equal to the width of the resin-impregnated glass fiber layeddown.

Winding machines of the prior art have provided a resin bath and meansfor wiping excess resin from the filaments passed through the resin bathimmediately adjacent the fiber supply. The resin-impregnated filamentsmust then travel to the point of layup, which, at times, may be a heightof 30 feet or more. Curing of the resin begins during such an extendedlength of travel with the result that the physical properties of thefilament wound tank are not optimum. To prevent this, the resin bath 32of the winding machine of this invention is located adjacent the layuparm on platform 28 and travels up and down the mast 23 with the layuparm. Resin and a catalyst for the resin are stored in separatecontainers 33 and 34 on the carriage and separate feed lines 35 and 36provided from each of the containers to carry the resin and catalystfrom the containers to suitable metering pumps 37 which meterpredetermined quantities of resin and catalyst through the separate feedlines to the resin bath adjacent the layup arm 31. The resin andcatalyst are mixedtogether with a suitable mixer 38 just before entryinto the resin bath. The glass fiber rovings 39, pulled from filamentsupply 21, pass upwardly through guides 40 and, just prior to layup,pass over a metering roll 41 mounted .in the resin bath 32 which picksup freshly mixed resin and deposits it uniformly onto the glassfilamentsrWiping orifices may be provided to remove excess resin fromthe filaments as they exit from the resin bath. The continuousresin-impregnated glass fiber rovings are wound in a generally helicalformation and extend spirally both upwardly and downwardly. It isdesirable to taper the outer wall as shown in FIG. 2, the filamentwindings being thicker in cross-section at the lower end than at thetop. This provides greater hoop strength for the tank at the lower end.

After the resin has cured sufficiently, access openings are cut in thetank where desired. The temporary rivets 15 holding the beams 13 to thearcuate liner panels 5 are removed and the temporary beams 13 removedthrough the top or side openings. Nozzles, fittings, and appurtenancesmay be installed in the tank using chopped and woven glass fiberreinforced resin. A colored coating may be applied after installation ofexterior noz zles,fittings, and appurtenances. The tent cover and thecenter support mast 9 are then removed.

An integral bottom is installed in the tank by sprayingresin-impregnated chopped fiber onto the tank support base and up ontothe tank side wall, the side wall and tank support base acting as a moldfor the resin-glass mix- By the means described a tank of large capacitycan be fabricated on-site with a minimum of hand labor, a minimum ofstructural necessities and a minimum number of machine fabricationfacilities.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A method of on-site fabrication of glass fiber, reinforced,plastic-resin tank structures, using a plurality of pre-fa'bricated,structural, arcuate liner panels of glass fiber, reinforced resin,comprising:

providing a base support for the tank structure, temporarily securingvertical support and alignment beams to the base support at spacedintervals corresponding to the width of the liner panels to define thecircumference of the tank structure, the beams extending the height ofthe tank structure,

providing a central beam extending upwardly from the base support havinga plurality of lateral arms extending therefrom into contact with thetemporary vertical support beams to support the side walls of thestructure during fabrication thereof,

temporarily securing by removable rivets the liner panels to thevertical support and alignment beams, the panels extending the height ofthe beams and abutting each other along their side edges in coincidencewith the vertical support beams to define the side walls of the tankstructure,

providing a top cover for the tank structure of glass fiber, reinforcedresin,

securing the top cover to the top edges of the liner panels,

applying a mixture of chopped glass fiber and resin over the joint areasbetween the abutting liner panels and between the top cover and the topedges of the liner panels to seal them and form an integral tankstructure,

mixing resin and catalyst together for impregnation of continuous glassfiber roving for winding of the side walls of the tank structure closelyadjacent the point of application of the resin-impregnated glass fiberto the side walls,

impregnating the glass fiber roving with the resin-catalyst mixture,

winding successive layers of the resin-impregnated continuous glassfiber roving around the outer surfaces of the liner panels in a helicalpattern extending spirally both upward and downward to provide hoopstrength for the tank structure,

removing the support and alignment beams temporarily secured to theliner panels from the interior of the tank structure after curing of theresin, and

applying resin-impregnated chopped glass fiber over the inner portion ofthe base support surrounded by the liner panels and joint areas betweenthe lower ends of the liner panels in the base support to form anintegral bottom wall for the tank structure.

2. A method for fabricating a tank structure on site by integrallybinding together a plurality of pre-formed interior liner panelstemporarily held in position by a plurality of elongated alignmentbeams, comprising the steps of (a) providing a base support for the tankstructure;

(b) forming an alignment structure by securing the elongated alignmentbeams to the base support in a generally vertical orientation at spacedintervals about the periphery of the desired tank configuration 6 suchthat the spaced intervals correspond to the width of the pre-formedliner panels; j

(c) placing the pre-formed liner panels in vertical edge abuttingrelationship about the periphery of the alignment structure such thatthe abutting vertical edges coincide with the position of the elongatedalignment beams;

(d) securing temporarilythe pre-formed liner panels to the elongatedalignment beams;

(c) binding the pre-formed liner panels together by wrapping the outsidesurface of the panels with a sufficient number of turns of a filamentcoated with uncured resin to provide the desired degree of hoop strengthto the tank;

(f) bonding the pre-formed tank sections permanently together by curingthe resin; and

(g) removing the elongated alignment beams.

3. The method as defined in claim 2, wherein step (b) includes the stepof securing the alignment beams in such a way as to define a cylindricaltank configuration and step (c) includes the step of placing pre-formedliner panels over the entire height of the cylindrical surface definedby the alignment beams.

4. The method as defined in claim 2, further including the step ofsealing the joints betwen the pre-formed liner panels prior to step (e)5. The method as defined in claim 2, wherein step (e) includes the stepsof wrapping the outside surface of the panels with glass fiber rovingsand coating the glass fiber rovings with a mixture of resin and catalystclosely adjacent the point of application of the glass fiber rovings tothe pre-formed liner panels.

6. The method as defined in claim 5, wherein step (e) further includesthe step of winding successive layers of resin coated glass fiberrovings around the outer surfaces of the pre-formed liner panels in ahelical pattern extending spirally both upwardly and downwardly of thetank structure.

7. The method as defined in claim 2, wherein step (b) further includesthe steps of (1) erecting a temporary vertically extending mast with thebase thereof being secured to the base support of the tank at the centerpoint of the desired tank base configuration,

(2) forming a top cover about the vertically extending mast adjacent thebase support of the tank,

(3) lifting the top cover to a position in which the top cover is toreside when the tank structure is completed.

8. The method as defined in claim 7, wherein step (b) further includesthe step of securing temporarily the alignment beams to the top cover.

9. The method as defined in claim 8 further including the step ofsealing the joints between the pre-formed liner panels and the jointsbetween the pre-formed liner panels and the top cover prior to step (e)10. The method as defined in claim 7, wherein step (2) further includesthe step of forming the top cover out of a plurality of pie-shapedsegments truncated at the inner end to form an opening through which thevertically extending mast may pass.

11. The method as defined in claim 7, wherein step (2) further includesthe step of providing a plurality of lateral arms connected at one endwith the vertically extending mast and connected at the other end withone of the alignment beams, respectively, to support the side walls ofthe tank structure during filament winding thereof.

12. The method as defined in claim 2, further including the step ofapplying resin-impregnated chopped fiber over the inner portion of thebase support surrounded by the pre-formed liner panels and the jointareas between the lower ends of the liner panels and the base support toform an integral bottom wall for the tank structure prior to removal ofthe temporary alignment beams.

13. The method as defined in claim 2, wherein, step (d) includestemporarily securing the alignment beams to the pre-formed liner panelsby removable rivets.

UNITED Cushman 254-93 Schneider -u 98-33 Elliott et a1. 15669 Snyder eta1. 15669 ,Broughton et al 156 -425 Martin 156-425 DANIEL J. FRITSCH,Primary Examiner 3,086,753 4/1963 3,626,836 12/.19'71 3,637,446 1/1 9723,461,009 8/1969 References Cited 5 2,729,268 1/1950 STATES PATENTS2,303,097 1 1957 Clements 156191 Carlini 156-484 Koontz 2203 Bastone eta1. 220-83 1o 15,' 17 2 425 Miron et al. 156--71 US. Cl. X.R.

1. A method of on-site fabrication of glass fiber, reinforced,plastic-resin tank structures, using a plurality of pre-fabricated,structural, arcuate liner panels of glass fiber, reinforced resin,comprising: providing a base support for the tank structure, temporarilysecuring vertical support and alignment beams to the base support atspaced intervals corresponding to the width of the liner panels todefine the circumference of the tank structure, the beams extending theheight of the tank structure, providing a central beam extendingupwardly from the base support having a plurality of lateral armsextending therefrom into contact with the temporary vertical supportbeams to support the side walls of the structure during fabricationthereof, temporarily securing by removable rivets the liner panels tothe vertical support and alignment beams, the panels extending theheight of the beams and abutting each other along their side edges incoincidence with the vertical support beams to define the side walls ofthe tank structure, providing a top cover for the tank structure ofglass fiber, reinforced resin, securing the top cover to the top edgesof the liner panels, applying a mixture of chopped glass fiber and resinover the joint areas between the abutting liner panels and between thetop cover and the top edges of the liner panels to seal them and form anintegral tank structure, mixing resin and catalyst together forimpregnation of continuous glass fiber roving for winding of the sidewalls of the tank structure closely adjacent the point of application ofthe resin-impregnated glass fiber to the side walls, impregnating theglass fiber roving with the resin catalyst mixture, winding successivelayers of the resin-impregnated continuous glass fiber roving around theouter surfaces of the liner panels in a helical pattern extendingspirally both upward and downward to provide hoop strength for the tankstructure, removing the support and alignment beams temporarily securedto the liner panels from the interior of the tank structure after curingof the resin, and applying resin-impregnated chopped glass fiber overthe inner portion of the base support surrounded by the liner panels andjoint areas between the lower ends of the liner panels in the basesupport to form an integral bottom wall for the tank structure.